Sonographic measurement of cervical length in twin pregnancies in threatened preterm labor.
D000293:Adolescent; D000328:Adult; D015992:Body Mass Index; D002584:Cervix Uteri / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D008423:Maternal Age; D007752:Obstetric Labor, Premature / Q000000981:diagnostic imaging*; D010146:Pain / Q000209:etiology; D010298:Parity; D011247:Pregnancy; D011272:Pregnancy, Multiple; D011446:Prospective Studies; D012044:Regression Analysis; D014427:Twins; D016216:Ultrasonography, Prenatal / Q000379:methods*; D014590:Uterine Contraction